Gearing actuator

ABSTRACT

A gearing actuator, particularly an electromechanical gearing actuator for an automated transmission of a motor vehicle, having at least one driving device for the transmission and a shifting motion in the transmission and one assembly for converting the rotational motion of a driving device to a translational motion of the assembly, which has one spindle and one sliding part movable on the spindle. The spindle ( 2 ) is provided with at least one continuation ( 1 ) extending in axial direction and mounted for absorbing transverse forces in needle sleeves or ball sleeves ( 3 ).

This application is a national stage completion of PCT/EP2004/008371filed Jul. 27, 2004 which claims priority from German Application SerialNo. 103 38 375.1 filed Aug. 21, 2003.

FIELD OF THE INVENTION

The invention concerns a gearing actuator for the preferably automatedtransmission of a motor vehicle.

BACKGROUND OF THE INVENTION

Vehicles with automated transmissions find an increasingly extended use.In the first place, to them belong commercially used vehicles, such asvans and trucks; those automated transmissions are also increasinglyused in sport designed, passenger or small cars. The object is torelieve the driver of the continuously required gear changes making acomfortable and, at the same time, reliable operation of the vehiclepossible.

To this end, the driver usually has a selector switch available forselection of a mode of operation so that he can choose among anautomatic mode, a manual shifting mode and a mode for a reverse gear.When the automatic mode is selected, an automatic ratio adaptationresults. Mainly in the transmissions designed for trucks, there areseveral possibilities for automation of the transmission. Pneumatic,hydraulic or electric systems can thus be used. In the first place, theselection depends on the vehicle class and on the kinds of energyrequired in the vehicles. The power need of the actuators used alsoconstitutes an important parameter. As actuators dependent on thesystem, pneumatic cylinders, hydraulic cylinders or electric motors areused which, via control elements, act upon the selection and shiftingdevices. The control elements, actuatable by an electric motor, atpresent are the construction of most favorable cost.

For a long time, it has been required for the manually shiftabletransmissions of vehicles that they be supplemented with anelectromechanical gearing actuator capable of automation.Electromechanical gearing actuators for gear change operations in avehicle transmission have, in turn, been known for a long time. Theseare mostly used in a transmission which either has been developedtogether with the gearing actuator or has adaptation elements to beattached or installed in the existing transmission and can operatetogether with the gearing actuator.

One typical gearing actuator has been described, for example in EP 0 377848 B1. This electromechanical gearing actuator has two axes of motiondisposed perpendicular to each other. One single selector finger isguided by two electric motors to the axes of motion. The selector fingermoved by the first electric motor here engages on the axis of motioncorresponding to a selection motion in a respective opening in thedifferent selector rods disposed in parallel side by side of each other.To shift a shifting set connected with a respective selector rod, bymoving the selector finger to the second axis of motion, the shiftingrod is moved by the second electric motor in direction of thelongitudinal axis thereof. Even though the motion mechanism of theselector finger for movement, along the two axes of movement disposedperpendicular to each other, does correspond to the preset selection andshifting of the manual shifting pattern and also to the selection andmotion of the respective shifting rod, this requires considerableinstallation space. The gearing actuator also needs a great number ofparts.

To overcome the disadvantages, in the Applicant's DE-A-101 43 325, anelectromechanical gearing actuator has been proposed and is to be fullyincluded in this application, which comprises a first electric motor forexecuting a selection motion of a shifting device in the transmission ofa motor vehicle and a second electric motor for executing a shiftingmotion of the shifting device. The control device belonging thereto canbe wholly or partly integrated in the gearing actuator or can bedesigned as an external control unit. The axis of rotation of the firstelectric motor and the axis of rotation of the second electric motor aredisposed parallel with each other.

To convert the rotation motion of the electromotors to a linear motion,ball circulation spindles driven, via a conversion of the appertainingmotor, are used here and can be designed as bevel gear drive, spur geardrive, worm drive, etc. Instead of a ball circulating spindle with balland nut movable thereon, it is possible to also use a thread, a spindleor a threaded spindle with screwed nuts corresponding thereto.

The ball circulating spindle for the shifting motion, described inconnection with a preferred embodiment, is located in a shiftingcylinder between two spring devices which operate in the direction ofmotion of the ball circulating spindle. If the ball circulating spindlefor the shifting motion rotates around its axis, the ball nut disposedthereon is moved in axial direction thereby acting upon the springdevice. The spring device is used as a force accumulator and prevents anoverload of the transmission gearshift or of the driving unit with theelectric motor, at the same time, taking care of a quick cutting throughof the sliding sleeve after reaching the synchronization point.

To support the torque introduced in the ball circulating spindle, a crewor a pin is used, which is axially movable within the shifting cylinder,but prevents a torsion of the ball nut relative to the shiftingcylinder. The ball nut, the spring device and the torque support arelodged in the shifting cylinder.

To connect the shifting cylinder with a relay lever and a selectorfinger, the axial motion of the shifting cylinder can be converted, viaa cylindrical pin or a ball cylinder pair, to a motion of the shiftingdevice extending perpendicular to the motion of the shifting cylinderalong the ball circulating spindle. A torsion of shifting shaft andselector finger, relative each other, can be prevented by a force orform locking connection.

If the ball circulating spindle for selection motion is shifted via theappertaining electric motor to a rotational motion, the ball nut movesin axial direction on the ball circulating spindle. The selector fingerconnected with the ball nut is secured against torsion. Selector fingerand ball nut can be designed in one piece here. The torque support canresult by an axial guide of the selector finger in the housing of thegearing actuator.

In a preferred embodiment, a cross clutch is provided between the shaftof the electric motor and the ball circulating spindle. By way of thecross clutch or also any other force or form locking clutch, such as amulti-cornered or polygonal section clutch, an axial offset betweenrotational shaft of the electric motor and ball circulating spindle isto be compensated. The axial forces appearing in the ball circulatingspindle are absorbed by a bearing of the ball circulating spindle in thehousing of the gearing actuator and not transmitted to the rotationalshaft of the electric motor.

However, the conventional ball circulating spindles, the same as theother conventional motion threads for gearing actuators, for convertingthe rotational motion to a translational motion are still affected withthe disadvantage that even though they are able to reliably absorb axialforces during a long period of time, radial or transverse forces canonly be absorbed to a certain extent. For the transverse forces to bebetter absorbable thus increasing the duration of the gearing actuator,linear guides have already been used, such as dovetail guides, roundguides, flat guides, prismatic guides and combinations thereof. But inmost cases, this kind of guide has a considerable negative effect on thedegree of efficiency. They are usually disposed parallel with the axisof the motion thread thereby demanding considerable space both in widthand in height.

The problem to be solved by this invention is to provide a gearingactuator in which a support of the transverse forces appearing on thespindle axis is ensured without requiring additional space in width.

SUMMARY OF THE INVENTION

According to the invention, it is provided that a single support ormultiple support of the transverse forces results on one cylinder inlinear continuation of the longitudinal axis of the spindle and thiswhile using roller or low-friction bearings. This kind of supportexclusively requires the already existing installation space of thegearing actuator in longitudinal and not in transverse direction. Atorsional safety is additionally provided here.

The single or multiple support of the spindle can result, for example,by one needle sleeve or also by one ball sleeve or several ball sleeves,which surround a section of the cylindrical continuation of the threadedspindle. One or more low-friction bearings can also be used instead ofneedle sleeves or ball sleeves or of needle bearings or ball bearings.

BRIEF DESCRIPTION OF THE DRAWING

The invention will now be described, by way of example, with referenceto the accompanying drawing in which:

FIG. 1 diagrammatically shows one section through the inventivelydeveloped gearing actuator in single version, and

FIG. 2 diagrammatically shows one section through the inventivelydeveloped gearing actuator in double version.

DETAILED DESCRIPTION OF THE INVENTION

The construction of a gearing actuator is well known to the expert andhas been described, in detail, in the introduction to the description sothat only the parts needed for understanding the invention have beenprovided with reference numerals.

FIG. 1 diagrammatically shows one section through a gearing actuatorwhich comprises one conversion device for converting a rotational motionto a translational motion, a spindle of which is designated with 2. Thespindle has one cylindrical continuation 1 mounted for absorbing thetransverse forces in the gearing actuator via one needle sleeve or ballsleeve 3.

In the embodiment, shown in FIG. 1, the gearing actuator is a singleversion, that is, it has only one spindle and only one movable partcoacting therewith. Only one electric motor (not shown) for driving thespindle 2 is also provided. The transverse forces are supported here viaa single support having only one needle sleeve or ball sleeve 3. Insteadof needle sleeves or ball sleeves, needle bearings or ball bearings canalso be provided or, if needed, low-friction bearings.

FIG. 2 diagrammatically shows one section through a gearing actuator,the spindle of which is, likewise, designated with 2. The spindle alsohas one cylindrical continuation or extension 1 mounted for absorbingthe transverse forces in the gearing actuator via one needle sleeve orone ball sleeve 3.

In the embodiment shown in FIG. 2 with multiple support, onecontinuation 1 is provided on both sides of the spindle, eachcontinuation being mounted in a needle sleeve or ball sleeve 3. Here thegearing actuator has a double function, that is, it has two spindlesdisposed parallel with each other which are driven by two electricmotors (not shown) for selection and shifting, such as more specificallydescribed in the Applicant's DE-A-101 43 325 cited above. Each spindleis identically provided with continuations mounted in the needle sleevesor ball sleeves for absorbing the transverse forces, but only thespindle 1 at bottom in the drawing with its continuations and sleeveshas been provided with reference numerals.

Instead of the needle sleeves or ball sleeves, it is also possible hereto use needle bearings or ball bearings and, if needed, alsolow-friction bearings.

It is clear that by virtue of the inventive construction of the gearingactuator, as already mentioned above, no additional installation spaceis required in radial direction for the single or multiple support ofthe continuations by way of needle sleeves and/or ball sleeves, but onlyin axial direction. Torsional safety is in addition provided.

REFERENCE NUMERALS

-   1 continuation-   2 spindle-   3 bearing sleeve

1-4. (canceled)
 5. An electromechanical gearing actuator for anautomated transmission of a motor vehicle, the gearing actuatorcomprising at least one driving device for one or more of a shiftingdevice and a shifting motion in the transmission and one assembly forconverting rotational motion of the driving device to a translationalmotion of the assembly, which has one spindle and one sliding part thatmoves on the spindle, the spindle (2) is provided with at least onecontinuation (1) extending in an axial direction which has at least onebearing (3) for absorbing transverse forces with which the transverseforces can be supported on the spindle (2).
 6. The gearing actuatoraccording to claim 5, wherein the at least one bearing (3) is at leastone needle sleeve.
 7. The gearing actuator according to claim 5, whereinthe at least one bearing (3) is at least one ball sleeve.
 8. The gearingactuator according to claim 5, wherein the at least one bearing (3) isat least one low-friction bearing.